Within restorative dentistry high customisability is often desired. This is due to the highly varied anatomy of the set of teeth for each human, which makes it very difficult to provide standard solutions that accommodate everyone. This is also the case for restorative dentistry using implants as will be discussed further herein.
The use of implants is a very specific branch of dentistry which has evolved rapidly within the last half century.
An implant is placed in the bone of the jaw where it is secured as the bone grows into very close apposition to the implant. This process is also known as osseointegration. In particular titanium has shown to have very good osseointegration properties and is currently the most preferred material to use for implants.
When osseointegration is complete and the implant is secure in the bone it may subsequently be used as a base for dental restorations and prosthetics. Typically so-called abutments are placed in the implant. The abutment serves as an interface between the implant and the final anatomical restoration, for example a crown or a bridge.
However, in some cases there are constraints on where an implant can be placed, this can for example be due to weak bone tissue or other considerations. Thus, depending on the anatomy of the patient the implant is often placed in different positions, for example at different angles. The abutment has to be designed to correct such difference in placement and angulation. There exists standard angulated abutments, however, these are only useable if the implant are placed within a specific angled interval.
Thus, in order to provide a higher flexibility for placing the implant different customisable abutments have been developed.
In general these can be categorised into two categories.
The first category relates to so-called one-piece customisable abutments, which is illustrated in FIG. 1a. 
FIG. 1a shows a dental prosthesis 101 comprising an implant 102, a one-piece customised abutment 103 and a restoration 104, e.g. in the form of a crown.
The implant 102 is placed in the bone tissue 105 of the jaw in an angled position along an implant axis A-A. In general, when referring to the angled position of the implant herein, it should be understood as being in relation to the general anatomy of the restoration and how the restoration protrudes from the jaw.
The one-piece customised abutment extends from the implant along an abutment emergence profile 110. The emergence profile is the shape of the one-piece customised abutment as it relates to the surrounding tissue, typically bone and gingiva, as it extends from the implant towards the exposed gingiva surface 111. The abutment typically ends sub-gingival, i.e. below the exposed gingiva surface, where it extends into the restoration 104. From the abutment the restoration extends along a restoration emergence profile 112 to the exposed gingiva surface from where it extends with an anatomic shape designed to be aesthetic and functional.
Unless explicitly stated otherwise the term “emergence profile” as used herein refers to the emergence profile of the abutment.
The one-piece customised abutment 103 is held in place by an implant screw 106, which is placed in a through-going bore 107 of the customised abutment 103 and engages with threads 108 in the implant to hold the screw and thereby the abutment in place.
The restoration 104 in the form of a crown is placed on the abutment. The crown is designed to fit between two neighbouring teeth 109. Typically the restoration and the abutment are cemented together.
As can be seen the abutment functions as an interface which can be designed so that the restoration can be designed to resemble a tooth as much as possible without being completely restricted to the angle of the placed implant.
The one-piece customised abutment 103 shown in FIG. 1a thus allow the dentist to place the implant much more freely than done before. However, since it is a monolithic one-piece abutment it can only be made of one material.
Typically the one-piece abutment is made of a metal, most commonly the same metal as the implant as this provides a robust and solid base for the restoration 104. However, since the restoration in many cases is made to resemble a tooth the restoration will typically be semi-transparent. This causes the metal of the abutment to shine through creating a greyish look of the final prosthesis which is not esthetical desirable.
Attempts have been made to form the one-piece customisable abutment of a material which has better aesthetic characteristics, such as zirconia. However, this has caused an increase in cases where the abutment breaks, in particular around the connection to the implant.
The other category is the two-piece semi-customisable abutments 203 as shown in FIG. 1 b, which solves some the problems related to the one-piece customisable abutments.
The two-piece abutment 203 is formed of an abutment base 220 and an abutment top 221. The abutment base 220 is provided as a standard unit which fits the specific implant 202. The abutment top 221 is customised and then attached, e.g. by cementing, to the abutment base.
The two-piece abutment 203 allows for the use of two materials. Thus, the abutment base 220 can be formed of a metal, e.g. titanium, and the abutment top 221 can be formed of e.g. zirconia. Thus, the abutment provides a base which is suitable for a dental restoration, such as a crown 204, having a high esthetical quality without risking that the abutment breaks.
However, the use of a standard abutment base 220 results in limitation to the customisation of the abutment top 221. For example in the circled critical area 230 the minimal thickness of the abutment top is compromised due to design restrictions applied by the standard shape of the abutment base.
Moreover, the emergence profile of the abutment, which is defined by the base emergence profile 222 of the abutment base and the top emergence profile 223 of the abutment top, is not fully customisable since the designer is not free to design the base emergence profile 222.
Accordingly, there exists a need to provide an abutment which gives the dentist and the dental laboratory a high degree of freedom of design while at the same time providing a dental prosthesis having high aesthetic and durable characteristics.